Methods will be developed and applied to the quantitation of pathways of carbohydrate and lipid metabolism. Using a split monkey brain preparation, an effect of insulin on glucose metabolism by the hypothalamus will be sought. From the fate of C14 of specifically C14- labeled fatty acids, the extent that alpha- and omega- oxidation contribute to fatty acid metabolism will be determined in muscle, liver, and brain during starvation and diabetes mellitus. The fate of the carbons of ketone bodies in these tissues will also be assessed including their possible contribution of intermediates for gluconeogenesis. Yields of C14O2 from specifically labeled fatty acids will be used as a measure of formation of free intermediates in fatty acid oxidation. The source of fructose in placenta will be measured by tracing its formation from C14- and H3-labeled glucose. For this the stereospecificity of the enzymes of the polyol pathway in regard to reduced nucleotide formation will be determined.